Window cleaning device

ABSTRACT

The present invention relates to a window cleaning device including a first cleaner and a second cleaner which are respectively attached on both sides of a window by magnetism. The device includes a first magnetic module included in the first cleaner; a second magnetic module included in the second cleaner; and a wheel part which is provided to at least one among the first and the second cleaner and moves the window cleaning device, wherein the wheel part includes a wheel having a plurality of holes at an external diameter part; a wheel cover made of an elastic material which surrounds the external diameter part of the wheel and generates frictional force by coming in contact with the window; and a wheel bearing which is connected to the wheel and delivers turning force, and a part of the wheel cover is inserted into the holes formed at the external diameter part of the wheel.

TECHNICAL FIELD

The present invention relates to a window cleaning device.

BACKGROUND ART

In general, windows installed on the walls of a building are easily polluted by external dust and pollutants, which may degrade their appearance and lighting performance. Therefore, it is preferable to frequently clean the windows installed on the walls of a building.

However, the outer side of the window is more difficult to clean than the inner side, and particularly, as higher buildings are increasingly constructed, cleaning the outer side of the windows may involve great risks.

DISCLOSURE Technical Problem

The technical problem of the present invention is for providing a structure of a driving wheel which enables a window cleaning device to move easily.

Technical Solution

A window cleaning device according to an exemplary embodiment of the preset invention includes a first cleaner and a second cleaner which are respectively attached on both sides of a window by magnetism, and the window cleaning device includes a first magnetic module included in the first cleaner; a second magnetic module included in the second cleaner; and a wheel part which is provided to at least one among the first and the second cleaner; and moves the window cleaning device, wherein the wheel part includes a wheel having a plurality of holes at an external diameter part; a wheel cover made of an elastic material which surrounds the external diameter part of the wheel and generates frictional force by coming in contact with the window; and a wheel bearing which is connected to the wheel and delivers turning force, and a part of the wheel cover is inserted into the holes formed at the external diameter part of the wheel.

Advantageous Effects

According to the embodiment of the present invention, the driving wheel of the window cleaning device is embodied by using the wheel made of metal and the wheel cover made of elastic material, which is inserted into holes formed at external diameter part of the wheel to be fixed thereto, so that the window cleaning device may easily move and durability may be enhanced.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view briefly illustrating the configuration of a window cleaning device according to an exemplary embodiment of the present invention.

FIG. 2 is a plan view illustrating the configuration of a first cleaner disposed on the inner side of a window, according to an exemplary embodiment.

FIG. 3 is a plan view illustrating the configuration of a second cleaner disposed on the outer side of a window, according to an exemplary embodiment.

FIG. 4 is a perspective view of a first cleaner according to an exemplary embodiment.

FIG. 5 is a view illustrating a movement path of a window cleaning device, according to an exemplary embodiment of the present invention.

FIG. 6 is a perspective view illustrating the configuration of a driving wheel installed in the window cleaning device, according to an exemplary embodiment of the present invention.

FIG. 7 is a perspective view illustrating the configuration of a wheel cover in FIG. 6.

FIG. 8 is a cross-sectional view illustrating the configuration of a wheel cover in FIG. 6.

FIG. 9 is a perspective view illustrating the configuration of a wheel in FIG. 6.

FIG. 10 is a cross-sectional view illustrating the configuration of a wheel in FIG. 6.

MODE FOR INVENTION

Hereinafter, a window cleaning device according to an exemplary embodiment of the present invention will be explained referring to FIG. 1 through FIG. 10. Hereinafter, embodiments may be modified in various ways, and the scope of the present invention is not limited by the embodiments. The embodiments are presented for explanation to a person ordinary skilled in the art. Therefore, shapes and sizes of the elements may be exaggerated for clear explanation.

FIG. 1 is a perspective view briefly illustrating the configuration of a window cleaning device according to an exemplary embodiment of the present invention. The window cleaning device may include two cleaners 100 and 200 to be attached to both sides of a window, respectively.

Referring to FIG. 1, the first cleaner 100 may be attached to an inner side of a window, and the second cleaner 200 may be attached to an outer side of the window. Alternatively, the first cleaner 100 may be attached to an outer side of a window and the second cleaner 200 may be attached to an inner side of the widow, when required.

The first cleaner 100 and the second cleaner 200 may be attached to both sides of a window, respectively, by using magnetic modules with magnetism, which are installed therein.

Further, when the first cleaner 100 is moved on the inner side of the window by an external or internal power source, the second cleaner 200 may be moved together with the first cleaner 100 by magnetic force between the magnetic modules of the first and second cleaners 100 and 200.

The second cleaner 200 may be provided with an attachment/detachment handle 250 to be easily attached/detached to/from a window, for example a handle 250, as illustrated in FIG. 1, and the first cleaner 100 may also be provided with an attachment/detachment handle (not shown) corresponding to the attachment/detachment handle 250 to be easily attached/detached.

Accordingly, a user can attach the window cleaning device to a window, using the attachment/detachment handles of the first and second cleaners 100 and 200, that is, the handles, and detach the first and second cleaners 100 and 200 from the window, using the handles after cleaning.

The window cleaning device according to an exemplary embodiment of the present invention may further include a remote controller (not shown) for a user to control the operations of the first and second cleaners 100 and 200.

As described above, the second cleaner 200 is passively moved by the magnetic force with the movement of the first cleaner 100 and a user can control the operation of a window cleaning device composed of the first and second cleaners 100 and 200 by controlling the movement of the first cleaner 100, using the remote controller.

Although a wireless type remote controller is exemplified in the exemplary embodiment for the convenience of a user, a wire type remote controller may be used or the window cleaning device may be manually controlled by a user.

On the other hand, the window cleaning device according to an exemplary embodiment of the present invention, in detail, the first cleaner 100 disposed on the inner side of a window may move along a predetermined movement path or may be equipped with a sensor (not shown), which detects dust, and move while determining a movement path that can improve cleaning efficiency.

Hereinafter, the first and second cleaners 100 and 200 will be described in more detail with reference to FIGS. 2 and 3.

FIG. 2 is a plan view illustrating the configuration of the first cleaner 100, that is, the configuration of the top to be brought in contact with a window, in both sides of the first cleaner 100.

Referring to FIG. 2, the first cleaner 100 may include a first frame 110, a plurality of first wheel parts 120, and a plurality of first magnetic modules 130.

The first frame 110 constitutes the body of the first cleaner 100, and the first wheel parts 120 and the first magnetic modules 130 may be connected and fixed to the first frame 110.

Shock-absorbers 140 to 143 may be disposed at the edge of the first frame 110 to minimize a shock when the window cleaning device collides with a protruding structure such as the frame of a window while moving. Sensors (not shown) are connected to the buffers 140 to 143, respectively, and when the sensors sense a shock, the first cleaner 100 can change the movement path.

For example, as illustrated in FIG. 2, the shock-absorbers 140 to 143 may be disposed at four corners of the first cleaner 100, respectively, and the connected sensors (not shown) can recognize that the first cleaner 100 has collided with the frame of a window by sensing a shock.

In detail, while the window cleaning device moves, when two shock-absorbers 140 and 141 at one side of the first cleaner 100 sense a shock, it is recognized that the side with the shock-absorbers 140 and 141 in the sides of the first cleaner 100 has collided with the frame of a window.

Although the first frame 110 of the first cleaner 100 has a rectangular cross-section in the exemplary embodiment, it does not limit the present invention, as an example, and may be implemented in various shapes such as a circular or polygonal cross-section.

The first cleaner 100 may include the first magnetic modules 130, which generate magnetic force such that the first and second cleaners 100 and 200 can be attached to both sides of a window, respectively.

For example, the first magnetic modules 130 may include a permanent magnet such as a neodium magnet, such that the first magnetic modules 130 can generate magnetic force together with second magnetic modules 233 of the second cleaner 200.

In more detail, the first magnetic modules 130 of the first cleaner 100 may include a magnet having a pole opposite to that of a magnet of the second magnetic modules 233 provided to the second cleaner 200, so that the first and second cleaners 100 and 200 disposed on both surfaces of a window can attract each other with magnetic force. Accordingly, the first and second cleaners 100 and 200 can be attached to the window, and be moved together.

According to another exemplary embodiment of the present invention, the magnetic modules 130 and 233 may include electromagnets, not the permanent magnets, or may include permanent magnets and electromagnets, as another exemplary embodiment.

The window cleaning device according to an exemplary embodiment of the present invention is not limited to the configuration including the first and second magnetic modules 130 and 233, and may include any configuration, provided that the first and second cleaners 100 and 200 can be attached and moved on a window therebetween.

For example, one of the first and second cleaners 100 and 200 may include a magnetic body such as a permanent magnet or an electromagnet and the other may include a metal body that can be attracted by magnetic force of the magnetic body.

As illustrated in FIG. 2, the first magnetic modules 130 may be implemented by four discs and may be disposed on the top, which is to be attached to a window, of the first cleaner 100.

The first magnetic modules 130 may be exposed toward the window, or may be disposed close to the top of the first cleaner 100 by specific covers.

Further, two or more first wheel parts 120 may be provided at the left and right sides of the first cleaner 100 to be partially exposed above the first frame 110, for example, as illustrated in FIG. 2, two wheel parts may be disposed at the left and right sides of the first cleaner 100, respectively, or four wheel parts may be disposed at the corners, respectively.

For example, the first wheel parts 120 may be rotated by a driver (not shown) such as a motor disposed inside the first frame 110. The first cleaner 100 can be moved in a predetermined direction on a window by the rotation of the first wheel parts 120.

The first cleaner 100 may not only move straight, but move along a curve, that is, may change the movement direction. For example, it is possible to change the movement direction of the first cleaner 100 by changing the rotational axes of the first wheel parts 120 or rotating the two first wheel parts 120 at the left and right sides, respectively, at different speeds.

The surfaces of the first wheel parts 120 may include, for example, fabric or rubber to generate predetermined frictional force against a window in rotating, and accordingly, the first cleaner 100 can easily move on the inner side of a window without idling. Further, the surfaces of the first wheel parts 120 may be made of a material that does not scratch a window in rotating.

When the first cleaner 100 is attached to a of a window by magnetic force of the first magnetic modules 130, reaction force perpendicular to the window may be applied to the first wheel parts 120. Therefore, as the first wheel parts 120 are rotated by the driver such as a motor, the first cleaner 100 can be moved on the inner side of a window by frictional force.

Further, as the first cleaner 100 is moved by the rotation of the first wheel parts 120, the second cleaner 200 attached to the opposite side, that is, the outer side of the window, can clean the window while moved together with the first cleaner 100 by the magnetic force.

FIG. 3 is a plan view illustrating the configuration of the second cleaner 200 according to an exemplary embodiment, that is, the configuration of the bottom to be brought in contact with a window, in both sides of the second cleaner 200.

Referring to FIG. 3, the second cleaner 200 may include a second frame 210, a plurality of second wheel parts 220, and a plurality of cleaning modules 230.

The second frame 210 may constitute a body of the second cleaner 200 and may be implemented in a plate structure having a shape corresponding to that of the first frame 110 described above, for example, a rectangular cross-section.

Further, the second wheel parts 220 are disposed on the bottom of the second frame 210 such that the second cleaner 200 can be moved by magnetic force with the movement of the first cleaner 100.

According to an exemplary embodiment, unlike the first wheel parts 120, the second wheel parts 220 may be connected not to a driver such as a motor, but to the second frame 210 by shafts to smoothly rotate with the movement of the second cleaner 200.

Accordingly, when the second cleaner 200 is moved together with the first cleaner 100 by magnetic force, the second wheel parts 220 may perform function similar to that of a bearing, by rotating.

Although the second wheel parts 220 are formed a cylindrical shape in FIG. 3, the present invention is not limited thereto, and for example, the second wheel parts 220 may be implemented by a spherical part such as a ball bearing.

The cleaning modules 230 are disposed on the bottom of the second frame 210 to be exposed to the outside, such that they can clean a side of a window, for example, the outer side where the second cleaner 200 is attached.

As illustrated in FIG. 3, each of the cleaning modules 230 may include a plurality of modules, for example, a cleaning pad 231, a second magnetic module 233, and a detergent ejection port 232, and may be implemented by four discs corresponding to the first magnetic modules 130 of the first cleaner 100.

Each of the four discs of the cleaning modules 230 may be rotated by a driver (not shown) such as a motor (not shown). Further, the cleaning modules 230 may protrude from a bottom surface of the second frame 210, at a predetermined distance, such that when attached to a window, the second cleaner 200 can clean the outer side of the window, using frictional force due to rotation of the cleaning modules 230.

The pad 231 made of fabric or rubber may be attached to the exposed surface of the cleaning module 230 such that foreign materials can be easily removed from the window by the frictional force in rotating. In this case, the pad 231 may be made of a material having a micro tip structure or porous structure to improve cleaning performance of the window cleaning device.

Further, the cleaning module 230 may have the detergent ejection port 232 for ejecting a detergent, and for example, the detergent ejection port 232 may be connected with a detergent container (not shown) and a pump (not shown) in the second cleaner 200, through a specific channel to be supplied with a detergent. Therefore, when cleaning a window, the cleaning module 230 can clean the window while ejecting a detergent onto the window through the detergent ejection port 232.

The second magnetic module 233 may be disposed the inside of the cleaning module 230, that is, under the bottom of the pad 231. The second magnetic module 233 has a shape corresponding to that of the first magnetic module 233 of the first cleaner 100 and generates magnetic force such that the first and second cleaners 100 and 200 can be attached to both sides of a window.

The second magnetic module 233 may be implemented by a magnetic body or metal body such as a permanent magnet or an electromagnet, and accordingly, the first and second cleaners 100 and 200 respectively on both sides of a window can be attached and moved on the window by being attracted to each other by the magnetic force.

For example, the cleaning module 230 may be disposed to correspond to the first magnetic module 130, and the second magnetic module 233 implemented by a neodium magnet having a polarity opposite to that of the first magnetic module 130 may be disposed inside the cleaning module 230.

Therefore, not only the first and second cleaners 100 and 200 can be attached to both sides of the window by the magnetic force between the first magnetic module 130 and the second magnetic module 233 of the cleaning module 230, but the first and second cleaners 100 and 200 can be integrally moved.

Further, a force is continuously applied, toward the window, to the cleaning module 230 by the magnetic force between the first and second magnetic modules 130 and 233 and the frictional force on the window correspondingly increases, when the cleaning module 230 rotates, such that the cleaning performance can be improved.

Referring to FIG. 3, a plurality of sub-cleaning modules 240 may be disposed at the corners of the second cleaner 200. Since the cleaning module 230 is disposed inside the second frame 210 and may be difficult to clean the edge of a window, the second cleaner 200 is provided with the sub-cleaning modules 240 to more easily clean the edge of the window.

The sub-cleaning modules 240 each include a roller (not shown) which is rotatably installed and a brush may be disposed around the surface of the roller. Therefore, the sub-cleaning modules 240 can remove foreign materials around the window frame while rotated by the frictional force against the window frame, when the second cleaner 200 moves along the window frame.

Further, the sub-cleaning modules 240 may perform the same function as that of the shock-absorbers 140 of the first cleaner 100. That is, the sub-cleaning modules 240 may minimize a shock and senses the shock, using a sensor provided therein, when the window cleaning device collides with a protruding structure such as a window frame.

Although the configuration of the window cleaning device according to an exemplary embodiment of the present invention was described above with reference to FIGS. 1 to 3, by exemplifying the window cleaning device cleaning only one side of a window, for example, the outer side of a window, this is only an exemplary embodiment of the present invention and the present invention is not limited thereto.

For example, the first cleaner 100 may also be provided with the cleaning modules 230 of the second cleaner 200, and accordingly, the window cleaning device may simultaneously clean both sides of a window.

FIG. 4 is a perspective view of a first cleaner 100 according to an exemplary embodiment. FIG. 4 illustrates an inner structure of a first cleaner 100. Hereinafter, descriptions of the same elements as those of FIGS. 1 to 3 in the first cleaner 100 illustrated in FIG. 4 will be omitted.

Referring to FIG. 4, a first frame 110 of the first cleaner 100 may include a first upper frame (not shown) and a first lower frame 111. A first magnetic module 130 may be disposed within the first upper frame (not shown) and the first lower frame 111.

Also, an attachment/detachment handle 150 for allowing a user to easily attach or detach the first cleaner 100 to or from a window, e.g., a handle may be connected to the first upper frame (not shown). Also, first wheel parts 120 and wheel driving parts 121 including motors for rotating the first wheel parts 120 may be fixed to the first lower frame 111.

A magnetic force control part 300 of the first cleaner 100 may include a rotation handle 311 and a rotation shaft 312 coupled to the rotation handle 311 and having a screw thread ascending in one direction on an outer surface thereof.

The first magnetic module 130 may have a through hole 135 formed at a center portion thereof, through which the rotation shaft 312 of the magnetic force control part 300 passes to be combined. The inner surface of the through hole 135 may have a screw threads corresponding to the screw thread of the rotation shaft 312.

The first frame 110 of the first cleaner 100 may include the first lower frame 111, and the first magnetic module 130 may be disposed inside of a guide 112 connected to the first lower frame 111.

When the rotation shaft 312 is rotated along one direction, the first magnetic module 130 is guided by the guide 112 to ascend or to descend through the combination of the screw thread of the rotation shaft 312 and the screw thread of the through hole 135.

When the first magnetic module 130 ascends, the distance between the first and second magnetic modules 130 and 233 decreases to increase magnetic force between the first and second magnetic modules 130 and 233. On the contrary, when the first magnetic module 130 descends, the distance between the first and second magnetic modules 130 and 233 increases to decrease magnetic force between the first and second magnetic modules 130 and 233.

According to an exemplary embodiment of the present invention, a user can rotate the rotation handle 311 in a first direction (for example counter clockwise direction) to ascend the first magnetic module 130, so that the distance between the first and second magnetic modules 130 and 233 is decreased to increase magnetic force.

On the contrary, a user can rotate the rotation handle 311 in a second direction (for example clockwise direction) to descend the first magnetic module 130, so that the distance between the first and second magnetic modules 130 and 233 is increased to decrease magnetic force.

According to another exemplary embodiment of the present invention, the magnetic force control part 310 may include a driving part such as a motor to rotate the rotation shaft 312, so that the first magnetic module 130 may ascend or descend automatically.

FIG. 5 is a view illustrating a movement path of a window cleaning device, according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the window cleaning device 10 may clean a window 400 repeating a first moving section in which the window cleaning device 10 moves from a side to an opposite side, and a second moving section in which the window cleaning device moves from the opposite side to the side.

For example, the movement path of the window cleaning device 10 includes a right-descending section 510 in which the window cleaning device 10 moves from a left end to a right end, and a left descending section 520 in which the window cleaning device 10 moves from the right end to the left end, and the right-descending section 510 and the left descending section 520 alternately repeats.

On the other hand, a descending angle may be determined according to an interval d of the movement path, which corresponds to adjacent two end position among movement path of the window cleaning device.

For example, in order to increase the interval d of the movement path, the descending angle of the window cleaning device 10 may be set to increase. As a result, the window may be more minutely cleaned but cleaning time increases.

On the contrary, in order to decrease the interval d of the movement path, the descending angle of the window cleaning device 10 may be set to decrease. As a result, the window may be more loosely cleaned but cleaning time decreases.

Further, the interval d of the movement path may be set to be a half of the size s of the window cleaning device 10, and a user may increase or decrease the interval d according to a requirement of cleaning time and cleaning elaborateness.

On the other hand, when the window cleaning device 10 moves along a right direction or a left direction, the window cleaning device 10 may slip downwardly due to gravitational force, so that the window cleaning device 10 may move with a descending angle that is greater than previously set descending angle.

The movement of the window cleaning device 10 may be unstable according to wheel parts 120 and 220 for moving the window cleaning device 10, for example the first wheel parts 120 of the first cleaner 100.

For example, when slip amount of the window cleaning device 10 exceeds expectation or the movement of the window cleaning device 10 is unstable due to damage such as an abrasion, the window cleaning device 10 may not move according to the movement path that is previously set, so that cleaning quality of the window cleaning device may be deteriorated.

In detail, as described referring to FIG. 1 through FIG. 4, as the first and second cleaning modules 100 and 200 move together with a window interposed therebetween through a magnetic force of a magnet such as permanent magnet, pressure is applied to the wheel parts 120 and 220 of the first and second cleaning modules 100 and 200, so that the wheel part parts 120 and 220 may be deformed or damaged or the outer surface of the wheel parts 120 and 220 may be worn away to leave a stain of elastic material such as a rubber on the window.

According to an exemplary embodiment of the present invention, the wheel parts 120 and 220 of the window cleaning device 10, or in detail, the first wheel parts 120 of the first cleaner 100, which moves the window cleaning device 10, includes a wheel made of metal, and a wheel cover inserted into holes formed at an external diameter part of the wheel and made of elastic material to easily move the window cleaning device and to enhance durability.

Hereinafter, the structure of the driving wheel of the window cleaning device according to the present invention will be explained referring to FIG. 6 through FIG. 10.

FIG. 6 is a perspective view illustrating the configuration of a driving wheel installed in the window cleaning device, according to an exemplary embodiment of the present invention. The driving wheel may include a wheel cover 600, a wheel 610 and a wheel bearing 620.

Referring to FIG. 6, the wheel 610 is made of metal and forms a body of the driving wheel, and the wheel cover 600 is made of elastic material for generating frictional force and surrounds the external diameter part of the wheel 610.

According to an exemplary embodiment of the present invention, the wheel 610 is formed through a cast molding by using aluminum or aluminum based alloy, and the wheel 610 has a plurality of holes formed at the external diameter part thereof.

The wheel 610 may be formed through two structures by a double injection molding.

The wheel cover 600 may be made of silicone, and a portion of the wheel cover 600 may be inserted into the holes formed at the external diameter part of the wheel 610.

As described above, when the wheel 610 is formed through cast molding using aluminum, durability of the driving wheel is enhanced. Especially, when the first and second cleaning modules 100 and 200 move together with a window interposed therebetween through a high magnetic force induced by magnet such as a permanent magnet, the deformation of the driving wheel, which may be induced by high pressure applied to the driving wheel, may be prevented.

Additionally, when the wheel cover 600 is made of silicone, the frictional force between a window and the driving wheel and the adhesive strength between the wheel cover 600 and the wheel 610 are enhanced to reduce slip of the window cleaning device 10 in a lower direction and running idle of the driving wheel. Further, leaving a stain of elastic material such as a rubber, which is induced by abrasion, is prevented.

Further, when a portion of the wheel cover 600 made of silicone is inserted into the hole formed at the external diameter part of the wheel 610, running idle between the wheel cover 600 and the wheel 610 is reduced.

On the other hand, the first wheel parts 120 of the first cleaning module 110 may be rotated by a driver (not shown) including for example a motor to move the first cleaner 100 along an inner surface of a window by a frictional force, the second cleaner 200 may move along the first cleaner 100 by a magnetic force, and the second wheel parts 220 may not be rotated by another driver but be freely rotated when the second cleaner 200 moves.

As a result, movement of the window cleaning device 10 is not affected by the rotation of the second wheel parts 220 of the second cleaner 200, but is directly affected by the rotation and the durability of the first wheel parts 120 of the first cleaner 100, and by the friction al force between the first wheel parts 120 and the window.

Therefore, according to an exemplary embodiment of the present invention, the first wheel parts 120 of the first cleaner 100 among the wheel parts 120 and 220 of the window cleaning device 10 may have the structure above mentioned referring to FIG. 6.

The wheel bearing 620 is connected to the wheel 610 to deliver turning force. For example, a side of the wheel bearing 620 may be inserted into the wheel 610 to be fixed thereto, making contact with the wheel 610, and an opposite side of the wheel bearing 620 may be connected to the wheel driving part 121 for rotating the first wheel parts 120 as shown in FIG. 4.

According to an exemplary embodiment of the present invention, the wheel bearing 620 may be made of polyoximethilene (POM) resin or POM based compound.

Hereinafter, the case in which the first wheel parts 120 of the first cleaning module 100 has the structure of the driving wheel according to embodiments of the present invention will be explained for example. However, the present invention is not limited as above. That is, the second wheel parts 220 of the second cleaner 200 may have the following structure. Further other wheel parts of the window cleaning device 10 may have the following structure.

FIG. 7 is a perspective view illustrating the configuration of a wheel cover 600 in FIG. 6, and FIG. 8 is a cross-sectional view illustrating the configuration of a wheel cover 600 in FIG. 6.

Referring to FIG. 7 and FIG. 8, the wheel cover 600 may be processed to be formed by silicone, and may include an outer part 601 surrounding the outer surface of the wheel 610 to generate frictional force between a window and the first wheel parts 120 and to generated adhesive strength between the wheel cover 600 and the wheel cover 600, and a plurality of inner parts 602 connected to the outer parts 602 and inserted into the plurality of holes, respectively.

That is, the outer part 601 of the wheel cover 600 surrounds the wheel 610 to generate the adhesive strength between the wheel cover 600 and the wheel 610 by elasticity, and the plurality of inner parts connected to the outer part 602 is inserted into the plurality of holes formed at the wheel 610 to be fixed thereto.

As a result, even when the strong pressure is applied to the first wheels 120 due to the magnetic force, running idle between the wheel cover 600 and the wheel 610 is prevented and the turning force of the wheel 610 is applied to the wheel cover 600.

FIG. 9 is a perspective view illustrating the configuration of a wheel in FIG. 6, and FIG. 10 is a cross-sectional view illustrating the configuration of a wheel in FIG. 6.

Referring to FIG. 9 and FIG. 10, the wheel 610 may be formed through cast molding by using aluminum, and may have a plurality of holes 612 into which the inner parts 602 of the wheel cover 600 are inserted.

For example, the external diameter part 611 include an outer face 613, an inner face 614 spaced apart from the outer face 613, and a plurality of supporting spokes 616 connecting the outer face 613 and the inner face 614 to define a plurality of holes 612.

Further, the wheel 610 may include two (or more than two) outer faces 613 spaced apart from each other to define a groove 615.

The groove 615 between the outer faces 613 enhances adhesive strength between the wheel 610 and the wheel cover 600.

The inner face 614 of the wheel 610 may be longer than the outer face 613 in length, so that the inner face 614 may be extended out of the outer face 613.

Hereinbefore, the present invention is explained through exemplary embodiments, but those are only examples and not limit the present invention. It will be apparent to those skilled in the art that various modifications and variation may be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 

1. A window cleaning device including a first cleaner and a second cleaner which are respectively attached on both sides of a window by magnetism, the window cleaning device comprising: a first magnetic module included in the first cleaner; a second magnetic module included in the second cleaner; and a wheel part which is provided to at least one among the first and the second cleaner and moves the window cleaning device, wherein the wheel part includes: a wheel having a plurality of holes at an external diameter part; a wheel cover made of an elastic material which surrounds the external diameter part of the wheel and generates frictional force by coming in contact with the window; and a wheel bearing which is connected to the wheel and delivers turning force, and a part of the wheel cover is inserted into the holes formed at the external diameter part of the wheel.
 2. The window cleaning device of claim 1, wherein the external diameter part comprises a plurality of supporting spokes for forming the holes between an outer face and an inner face.
 3. The window cleaning device of claim 2, wherein the wheel comprises two outer faces spaced apart from each other to form a groove therebetween.
 4. The window cleaning device of claim 2, wherein the external diameter part of the wheel has the inner face extending out of the outer face.
 5. The window cleaning device of claim 2, wherein a portion of the wheel bearing is inserted into the inner face of the external diameter part, such that the wheel bearing makes contact with the inner face.
 6. The window cleaning device of claim 1, wherein the first cleaner, which is attached on an inner side of the window, comprises at least two wheel parts.
 7. The window cleaning device of claim 6, wherein the first cleaner comprises a driver for rotating the wheel part, and the second cleaner attached on an outer side of the window moves through magnetic force along the first cleaner.
 8. The window cleaning device of claim 1, wherein the wheel cover comprises silicone.
 9. The window cleaning device of claim 1, wherein the wheel comprises aluminum.
 10. The window cleaning device of claim 1, wherein the wheel is formed through two structures by a double injection molding.
 11. The window cleaning device of claim 1, wherein the wheel bearing comprises polyoxymethilene (POM) resin. 